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ddi_iopb_alloc, ddi_iopb_free - allocate and free non-sequentially accessed memory

#include <sys/ddi.h>
#include <sys/sunddi.h>

int ddi_iopb_alloc(dev_info_t *dip, ddi_dma_lim_t *limits, 
 uint_t length, caddr_t *iopbp);

void ddi_iopb_free(caddr_t iopb);

These interfaces are obsolete. Use ddi_dma_mem_alloc(9F) instead of ddi_iopb_alloc(). Use ddi_dma_mem_free(9F) instead of ddi_iopb_free().

dip

limits

length

iopbp

iopb

The ddi_iopb_alloc() function allocates memory for DMA transfers and should be used if the device accesses memory in a non-sequential fashion, or if synchronization steps using ddi_dma_sync(9F) should be as lightweight as possible, due to frequent use on small objects. This type of access is commonly known as consistent access. The allocation will obey the alignment and padding constraints as specified in the limits argument and other limits imposed by the system.

Note that you still must use DMA resource allocation functions (see ddi_dma_setup(9F)) to establish DMA resources for the memory allocated using ddi_iopb_alloc().

In order to make the view of a memory object shared between a CPU and a DMA device consistent, explicit synchronization steps using ddi_dma_sync(9F) or ddi_dma_free(9F) are still required. The DMA resources will be allocated so that these synchronization steps are as efficient as possible.

The ddi_iopb_free() function frees up memory allocated by ddi_iopb_alloc().

The ddi_iopb_alloc() function returns:

DDI_SUCCESS

DDI_FAILURE

These functions can be called from user, interrupt, or kernel context.

See attributes(5) for a description of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Stability Level	Obsolete

attributes(5), ddi_dma_free(9F), ddi_dma_mem_alloc(9F), ddi_dma_mem_free(9F), ddi_dma_setup(9F), ddi_dma_sync(9F), ddi_mem_alloc(9F), ddi_dma_lim_sparc(9S), ddi_dma_lim_x86(9S), ddi_dma_req(9S)

Writing Device Drivers

This function uses scarce system resources. Use it selectively.